Piston



1 .im` 5, 1937. A R. E. DAY 2,066,613;

` PIsToN' lFiled March 1, 1926 INVENTOR y BY 4 v nanas an. s, 19a-iPISTGN my n. my, seattle. wasn.

. i Application March l, 1926, ScriaiNo. 91,407

4 calms. (ci. soa-11) My invention relates to improvements in pistons.and an object of my invention is to provide a piston of light weightmaterial, having a relatively high coemcient of expansion and adapted sior use'in an enginecylinder having a lower coemcient of expansion,which piston is constructed so that the diametrical expansion due toheat lot those portions of the piston that bear against the cylinderwall is minimized or entirely neu- 10 tralized or even rendered4negative if desired, thereby making it practical to nt the piston to anengine cylinder with a minimum amount of clearance,

A more speciiic object is to provide a piston of 1I ligtweight material,as aluminum or aluminum alloy, said n embodying a piston head,and havingslipper sections forming thrust faces at the sides of the piston andhaving means connecting each thrust face with the piston head at mdiierent points for supporting the thrust face and for tending 'to'movethe slipper section inwardly without distorting the shapefof the same inresponse to expansion oi' the piston head.

Other and more specific objects will be appag rent from the followingdescription taken in connection with the accompanying drawing.

Y In .the drawing Figure 1 is a view in elevationofa piston constructionembodying my invention.

-m Rss. 2 and 3 are secticnla views o thesame on broken lines 2 2 and ofFig. 1.

Fig. 4 is an elevation of a piston showing the slipper sectionsextending substantially all of the way around the piston. Y 35 Likereference numerals designate like parts throughout the several views.

In the onstruction of pistons for internal combustion engines it ishighly desirable that the pistons be made of metal that is light inweight, 4o strong andpossessed of' high heat conductivity. At thepresent time aluminum and aluminum alloys are extensively used. lOneserious objection to the use of aluminum and its alloys-inpiston4construction is due to the fact that the V.45 co-emcient of thermalexpansion oi' aluminum is substantially higherA than that of the ironfrom which engine cylinders are ordinarily made. This thermal conditionsare such that'the. maximum lili'I clearance is present. On the otherhandif not light weight materia in which the-supper or skirt sections at thesides oi! the piston, 'that take the side thrust; are connected with thepiston head in such a manner as to1 minimize lor entirely neutraliiteVany outward movement or diametrical expansion oi.' said slipper sectionsdue to heat, the movement produced by expansion oi' the piston headcausing the mechanism that is connected with the slipper sections totend to draw said slishnpper sections inwardly without distorting their,

pe. i In the accompanying drawing, Figs. 1, 2, and 3, show a pistonembodying a cup shaped head l0 connected by depending integral, spacedapart supports li with pin bosses |62 o'f the usual form. 'Ihe piston isrovided on the sides at right anglesto the wrist pin bosses I2 with two4 oDpOsitely disposed slipper sections I3 that are 25 each connectedwith the wrist pin bosses by two or more divergent struts i4, and thatafford thrust faces for taking the side thrust dueto eccentricity of thecrank shaft. 'I'he points of connection of the struts I I withtheslipper sections II3 is necessarily closer together than the points ofconnection ofsaid struts with theA wrist pin bosses so that when saidwrist pin bosses are moved apart the struts will tend to draw theslipper sections inwardly. The distance between 35 the points ofconnection ofthe two supports ll with the ypiston head I0 will determinethe amount of movement that will be produced between the two wrist pinbosses and said distance may be varied in the construction of thepiston. 40'

The connection of the wrist pin bosses with the 'slipper sections isnecessarily made in such a manner that the shape of the slipper sectionswill not be distorted by the comparatively slight movements of the wristpin bosses. Slots i5 sep- 45 arate the slipper sections it fromthepiston headm.

' The amount of movement which the struts will tend -toiimpart to the'slipper sectionsby a given movement ofthe wrist pin bosses will vary inproportion.. to the angle of divergence between the struts that connectwith the respective wrist pin bosses.

Asshown in Fig. V2 the struts M connecting the slipper sections with thewrist pin bosses are 5u curved, said curved struts having a tendency, asabove stated, to move the slipper sections inwardly when the wrist pinbosses are moved apart. In addition, since said struts are some- 5 whatresilient due to their curved form they may yield slightly as may bedesirable under certain conditions. With reference to this embodiment ofthe invention, each diagonal strut i4, which ex tends in divergingrelation from the skirt section or slipper to one of the bosses, isbowed in a region located a substantial distance inwardly from its pointof juncture with the skirt, and in the illustrated example the strutsare shown, by way of example, as bowed throughout the major portion oftheir breadth. This feature, i. e. the bowing of the struts, hasimportant'advantages in improving the operation of the piston under allconditions of engine operation, particularly under conditions when theentire piston heats up to relatively high temperatures and the toggleaction of the struts is ineffective to control the diameter of theskirt. In this embodiment it is also preferred that at least asubstantial portion of each strut i4 in its breadth where it joins ormerges into the boss l2 extends at a relatively fiat angle transverselywith respect to the axis of the pin bosses, this angle, as shown, beingless than forty degrees.

As a consequence of the improved construction,

it will be seen that the diverging arrangement of the struts permits apredetermined control of the skirt diameter asa consequence of thetoggle action exerted by the struts tending to draw the thrust facesinwardly when said bosses tend to move apart upon thermal expansion ofthe head, and the curvature or bowing of said struts, aided by thedescribed angularity thereof, provides sufficient flexibility oryieldability so that upon failure of said struts to control the skirtdiameter,

such as by reason of excessive heating of the p iston, said struts willflex or bend upon expansion of said skirt against the cylinder wall.Seizure and scoring of the piston under such conditions are greatlyminimized. The piston shown in Fig. 4 is similar to the piston disclosedin the preceding figures except that the skirt or slipper sections 22 ofthe same extend farther around the sides of the piston and are separatedfrom each other and from the wrist pin 5 supports 2l by narrow slots22'.

I have shown a pair of struts connecting each slipper section with thewrist pin bosses but, if desired, more than one pair may be so connectedwith each slipper section.

55 The operation oi my piston is as follows:

In installation, the slipper sections may be fitted closely Within thecylinders so that the piston will run smoothly and quietly and withoutpiston slap when the engine is cold. As the pis- 60 ton becomes heatedby the operation of the engine all parts of the piston will expand byheat 70 the slipper sections inwardly as the inner ends of said strutsare moved apart. By varying the angle between the struts as hereinbeforedescribed the movement apart of the members that support the inner endsof the struts, due to expansion of the 75 piston head, may be made topartially or entirely counteract expansion of the struts and slippersections or may even be made to draw the slipper sections inwardslightly as the piston becomes heated. If only one slipper section isconnected to the wrist pin bosses by convergent supports and the otherslipper section is otherwise supported the expansion of the thrust facesof the piston may be greatly minimized and beneficial results obtained.

It is convenient to connect the struts to the 10 wrist pin bosses but itwill be understood that said struts may be connected directly with thepiston head or with any suitable supports that extend downwardly from,and are subject to the expansion of the piston head. 1"

If desired the supports that connect the wrist pin bosses with thepiston head may be made so that they will yield slightly if subjected tomore than the usual strain.

In some constructions I prefer to proportion 20 the strength of theseveral parts so that expansion of thepiston head up to a predeterminedamount will ktend to draw the slipper sections inwardly but furtherexpansion of said head will be taken up in other ways and will notproduce any fur- 25 ther inward movement of the slipper sections.

The foregoing description and accompanying drawing clearly disclose apreferred embodiment of my invention but it will be understood that thisdisclosure is merely illustrative and that such 30 changes andvariations in this piston may be made as are within the scope and spiritof the following claims.

I claim:

1. A piston for use in an engine cylinder comprising a head, two bosscarrying supports extending downwardly from opposite sides of said head,coaxial piston pin bosses carried by said supports, a skirt constructedto form arcuate thrust faces at opposite sides of the piston be- 40tween said boss carrying supports, a pair of struts connecting eachthrust face with said supports, each pair of struts extending indiverging relation from the skirt to said supports and each strut beingbowed throughout a, substantial portion of its breadth, the skirt beingsupported from the head entirely through the medium of said pairs ofstruts, the diverging arrangement of the struts permitting apredetermined control of the skirt diameter as a consequence of a toggleaction exerted by the struts tending to draw the thrust faces inwardlywhen said bosses tend to move apart upon thermal expansion of the head,and the bowing of said struts providing sufcient flexibility so thatupon failure of said struts to control the skirt diameter by reason ofexcessive heating of the piston said struts will flex upon expansion ofsaid skirt against the cylinder wall.

2. A piston for use in an engine cylinder comprising a head, two bosscarrying supports extending downwardly from opposite sides of said head,coaxial piston pin bosses carried by said supports, a, skirt constructedto form arcuate thrust faces at opposite sides of the piston betweensaid boss carrying supports/a pair of diy agonal struts extending indiverging relation from a thrust face to said supports and each strutbeing bowed in a region located a substantial distance inwardly from itspoint of juncture with the skirt, the diverging arrangement of thestruts permitting a predetermined control of the skirt diameter as aconsequence of a toggle action exerted by the struts tending to draw thethrust faces inwardly when said bosses tend to move apart upon thermalexpansion of the head, and

aoeaeie ing of 'the piston when the skirt diameter is not controlled asa result oi said toggle action the struts will iiex upon expansion ofsaid thrust faces against the cylinder wall.

3. A piston according to claim i in which a part of each of the strutsextends at an angle of less than forty degress with the axis of thepiston pin 4. A piston for use in an engine cylinder comprising a head,two boss carrying supports en tending downwardly from opposite sides ofsaid head, coaxial piston pin Bosses carried ,by said supports, a skirtconstructed to form arcuate tlirust faces at opposite sides oi thepiston between said boss carrying supports, a pair of struts connectinga thrust face with said supports and extending in diverging relationfrom the skirt to said supports, each strut being bowed throughout themajor portion of its breadth, the diver-ging arrangementoi the strutspermitting a predetermined control oi the skirt diameter as a conse-Aquence of a toggle action exerted by the struts tending to draw thethrust faces inwardly when isaid bosses tend to move apart upon thermalexpansion of the head, and the angularity and howing of said strutsproviding sumcient flexibility so that upon failure of said struts tocontrol the skirt diameter such as hy reason oi excessive heating ofthe'piston said struts will ex upon expansion of said skirt against thecylinder wall.

, RAY n. nur. v

